Mike Waltz is being nominated to become the U.S. ambassador to the United Nations.
President Trump announced the nomination on the same day reports surfaced that Waltz would resign as his national security adviser.
Waltz faced scrutiny for mistakenly adding a reporter to a Signal group chat that discussed plans for a military strike.
In a post, Trump said that in the interim, Secretary of State Marco Rubio will serve as National Security Advisor, while continuing his strong leadership at the State Department.
Republican Congresswoman Elise Stefanik of New York was the UN nominee until the White House withdrew it, citing a slim House GOP majority.